arch/x86_64/kernel/hpet.c

   1 #include <linux/kernel.h>
   2 #include <linux/sched.h>
   3 #include <linux/init.h>
   4 #include <linux/mc146818rtc.h>
   5 #include <linux/time.h>
   6 #include <linux/clocksource.h>
   7 #include <linux/ioport.h>
   8 #include <linux/acpi.h>
   9 #include <linux/hpet.h>
  10 #include <asm/pgtable.h>
  11 #include <asm/vsyscall.h>
  12 #include <asm/timex.h>
  13 #include <asm/hpet.h>
  14
  15 #define HPET_MASK       0xFFFFFFFF
  16 #define HPET_SHIFT      22
  17
  18 /* FSEC = 10^-15 NSEC = 10^-9 */
  19 #define FSEC_PER_NSEC   1000000
  20
  21 int nohpet __initdata;
  22
  23 unsigned long hpet_address;
  24 unsigned long hpet_period;      /* fsecs / HPET clock */
  25 unsigned long hpet_tick;        /* HPET clocks / interrupt */
  26
  27 int hpet_use_timer;             /* Use counter of hpet for time keeping,
  28                                  * otherwise PIT
  29                                  */
  30
  31 #ifdef  CONFIG_HPET
  32 static __init int late_hpet_init(void)
  33 {
  34         struct hpet_data        hd;
  35         unsigned int            ntimer;
  36
  37         if (!hpet_address)
  38                 return 0;
  39
  40         memset(&hd, 0, sizeof(hd));
  41
  42         ntimer = hpet_readl(HPET_ID);
  43         ntimer = (ntimer & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT;
  44         ntimer++;
  45
  46         /*
  47          * Register with driver.
  48          * Timer0 and Timer1 is used by platform.
  49          */
  50         hd.hd_phys_address = hpet_address;
  51         hd.hd_address = (void __iomem *)fix_to_virt(FIX_HPET_BASE);
  52         hd.hd_nirqs = ntimer;
  53         hd.hd_flags = HPET_DATA_PLATFORM;
  54         hpet_reserve_timer(&hd, 0);
  55 #ifdef  CONFIG_HPET_EMULATE_RTC
  56         hpet_reserve_timer(&hd, 1);
  57 #endif
  58         hd.hd_irq[0] = HPET_LEGACY_8254;
  59         hd.hd_irq[1] = HPET_LEGACY_RTC;
  60         if (ntimer > 2) {
  61                 struct hpet             *hpet;
  62                 struct hpet_timer       *timer;
  63                 int                     i;
  64
  65                 hpet = (struct hpet *) fix_to_virt(FIX_HPET_BASE);
  66                 timer = &hpet->hpet_timers[2];
  67                 for (i = 2; i < ntimer; timer++, i++)
  68                         hd.hd_irq[i] = (timer->hpet_config &
  69                                         Tn_INT_ROUTE_CNF_MASK) >>
  70                                 Tn_INT_ROUTE_CNF_SHIFT;
  71
  72         }
  73
  74         hpet_alloc(&hd);
  75         return 0;
  76 }
  77 fs_initcall(late_hpet_init);
  78 #endif
  79
  80 int hpet_timer_stop_set_go(unsigned long tick)
  81 {
  82         unsigned int cfg;
  83
  84 /*
  85  * Stop the timers and reset the main counter.
  86  */
  87
  88         cfg = hpet_readl(HPET_CFG);
  89         cfg &= ~(HPET_CFG_ENABLE | HPET_CFG_LEGACY);
  90         hpet_writel(cfg, HPET_CFG);
  91         hpet_writel(0, HPET_COUNTER);
  92         hpet_writel(0, HPET_COUNTER + 4);
  93
  94 /*
  95  * Set up timer 0, as periodic with first interrupt to happen at hpet_tick,
  96  * and period also hpet_tick.
  97  */
  98         if (hpet_use_timer) {
  99                 hpet_writel(HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
 100                     HPET_TN_32BIT, HPET_T0_CFG);
 101                 hpet_writel(hpet_tick, HPET_T0_CMP); /* next interrupt */
 102                 hpet_writel(hpet_tick, HPET_T0_CMP); /* period */
 103                 cfg |= HPET_CFG_LEGACY;
 104         }
 105 /*
 106  * Go!
 107  */
 108
 109         cfg |= HPET_CFG_ENABLE;
 110         hpet_writel(cfg, HPET_CFG);
 111
 112         return 0;
 113 }
 114
 115 static cycle_t read_hpet(void)
 116 {
 117         return (cycle_t)hpet_readl(HPET_COUNTER);
 118 }
 119
 120 static cycle_t __vsyscall_fn vread_hpet(void)
 121 {
 122         return readl((void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
 123 }
 124
 125 struct clocksource clocksource_hpet = {
 126         .name           = "hpet",
 127         .rating         = 250,
 128         .read           = read_hpet,
 129         .mask           = (cycle_t)HPET_MASK,
 130         .mult           = 0, /* set below */
 131         .shift          = HPET_SHIFT,
 132         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 133         .vread          = vread_hpet,
 134 };
 135
 136 int hpet_arch_init(void)
 137 {
 138         unsigned int id;
 139         u64 tmp;
 140
 141         if (!hpet_address)
 142                 return -1;
 143         set_fixmap_nocache(FIX_HPET_BASE, hpet_address);
 144         __set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VSYSCALL_NOCACHE);
 145
 146 /*
 147  * Read the period, compute tick and quotient.
 148  */
 149
 150         id = hpet_readl(HPET_ID);
 151
 152         if (!(id & HPET_ID_VENDOR) || !(id & HPET_ID_NUMBER))
 153                 return -1;
 154
 155         hpet_period = hpet_readl(HPET_PERIOD);
 156         if (hpet_period < 100000 || hpet_period > 100000000)
 157                 return -1;
 158
 159         hpet_tick = (FSEC_PER_TICK + hpet_period / 2) / hpet_period;
 160
 161         hpet_use_timer = (id & HPET_ID_LEGSUP);
 162
 163         /*
 164          * hpet period is in femto seconds per cycle
 165          * so we need to convert this to ns/cyc units
 166          * aproximated by mult/2^shift
 167          *
 168          *  fsec/cyc * 1nsec/1000000fsec = nsec/cyc = mult/2^shift
 169          *  fsec/cyc * 1ns/1000000fsec * 2^shift = mult
 170          *  fsec/cyc * 2^shift * 1nsec/1000000fsec = mult
 171          *  (fsec/cyc << shift)/1000000 = mult
 172          *  (hpet_period << shift)/FSEC_PER_NSEC = mult
 173          */
 174         tmp = (u64)hpet_period << HPET_SHIFT;
 175         do_div(tmp, FSEC_PER_NSEC);
 176         clocksource_hpet.mult = (u32)tmp;
 177         clocksource_register(&clocksource_hpet);
 178
 179         return hpet_timer_stop_set_go(hpet_tick);
 180 }
 181
 182 int hpet_reenable(void)
 183 {
 184         return hpet_timer_stop_set_go(hpet_tick);
 185 }
 186
 187 /*
 188  * calibrate_tsc() calibrates the processor TSC in a very simple way, comparing
 189  * it to the HPET timer of known frequency.
 190  */
 191
 192 #define TICK_COUNT 100000000
 193 #define TICK_MIN   5000
 194 #define MAX_TRIES  5
 195
 196 /*
 197  * Some platforms take periodic SMI interrupts with 5ms duration. Make sure none
 198  * occurs between the reads of the hpet & TSC.
 199  */
 200 static void __init read_hpet_tsc(int *hpet, int *tsc)
 201 {
 202         int tsc1, tsc2, hpet1, i;
 203
 204         for (i = 0; i < MAX_TRIES; i++) {
 205                 tsc1 = get_cycles_sync();
 206                 hpet1 = hpet_readl(HPET_COUNTER);
 207                 tsc2 = get_cycles_sync();
 208                 if (tsc2 - tsc1 > TICK_MIN)
 209                         break;
 210         }
 211         *hpet = hpet1;
 212         *tsc = tsc2;
 213 }
 214
 215 unsigned int __init hpet_calibrate_tsc(void)
 216 {
 217         int tsc_start, hpet_start;
 218         int tsc_now, hpet_now;
 219         unsigned long flags;
 220
 221         local_irq_save(flags);
 222
 223         read_hpet_tsc(&hpet_start, &tsc_start);
 224
 225         do {
 226                 local_irq_disable();
 227                 read_hpet_tsc(&hpet_now, &tsc_now);
 228                 local_irq_restore(flags);
 229         } while ((tsc_now - tsc_start) < TICK_COUNT &&
 230                 (hpet_now - hpet_start) < TICK_COUNT);
 231
 232         return (tsc_now - tsc_start) * 1000000000L
 233                 / ((hpet_now - hpet_start) * hpet_period / 1000);
 234 }
 235
 236 #ifdef CONFIG_HPET_EMULATE_RTC
 237 /* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
 238  * is enabled, we support RTC interrupt functionality in software.
 239  * RTC has 3 kinds of interrupts:
 240  * 1) Update Interrupt - generate an interrupt, every sec, when RTC clock
 241  *    is updated
 242  * 2) Alarm Interrupt - generate an interrupt at a specific time of day
 243  * 3) Periodic Interrupt - generate periodic interrupt, with frequencies
 244  *    2Hz-8192Hz (2Hz-64Hz for non-root user) (all freqs in powers of 2)
 245  * (1) and (2) above are implemented using polling at a frequency of
 246  * 64 Hz. The exact frequency is a tradeoff between accuracy and interrupt
 247  * overhead. (DEFAULT_RTC_INT_FREQ)
 248  * For (3), we use interrupts at 64Hz or user specified periodic
 249  * frequency, whichever is higher.
 250  */
 251 #include <linux/rtc.h>
 252
 253 #define DEFAULT_RTC_INT_FREQ    64
 254 #define RTC_NUM_INTS            1
 255
 256 static unsigned long UIE_on;
 257 static unsigned long prev_update_sec;
 258
 259 static unsigned long AIE_on;
 260 static struct rtc_time alarm_time;
 261
 262 static unsigned long PIE_on;
 263 static unsigned long PIE_freq = DEFAULT_RTC_INT_FREQ;
 264 static unsigned long PIE_count;
 265
 266 static unsigned long hpet_rtc_int_freq; /* RTC interrupt frequency */
 267 static unsigned int hpet_t1_cmp; /* cached comparator register */
 268
 269 int is_hpet_enabled(void)
 270 {
 271         return hpet_address != 0;
 272 }
 273
 274 /*
 275  * Timer 1 for RTC, we do not use periodic interrupt feature,
 276  * even if HPET supports periodic interrupts on Timer 1.
 277  * The reason being, to set up a periodic interrupt in HPET, we need to
 278  * stop the main counter. And if we do that everytime someone diables/enables
 279  * RTC, we will have adverse effect on main kernel timer running on Timer 0.
 280  * So, for the time being, simulate the periodic interrupt in software.
 281  *
 282  * hpet_rtc_timer_init() is called for the first time and during subsequent
 283  * interuppts reinit happens through hpet_rtc_timer_reinit().
 284  */
 285 int hpet_rtc_timer_init(void)
 286 {
 287         unsigned int cfg, cnt;
 288         unsigned long flags;
 289
 290         if (!is_hpet_enabled())
 291                 return 0;
 292         /*
 293          * Set the counter 1 and enable the interrupts.
 294          */
 295         if (PIE_on && (PIE_freq > DEFAULT_RTC_INT_FREQ))
 296                 hpet_rtc_int_freq = PIE_freq;
 297         else
 298                 hpet_rtc_int_freq = DEFAULT_RTC_INT_FREQ;
 299
 300         local_irq_save(flags);
 301
 302         cnt = hpet_readl(HPET_COUNTER);
 303         cnt += ((hpet_tick*HZ)/hpet_rtc_int_freq);
 304         hpet_writel(cnt, HPET_T1_CMP);
 305         hpet_t1_cmp = cnt;
 306
 307         cfg = hpet_readl(HPET_T1_CFG);
 308         cfg &= ~HPET_TN_PERIODIC;
 309         cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
 310         hpet_writel(cfg, HPET_T1_CFG);
 311
 312         local_irq_restore(flags);
 313
 314         return 1;
 315 }
 316
 317 static void hpet_rtc_timer_reinit(void)
 318 {
 319         unsigned int cfg, cnt, ticks_per_int, lost_ints;
 320
 321         if (unlikely(!(PIE_on | AIE_on | UIE_on))) {
 322                 cfg = hpet_readl(HPET_T1_CFG);
 323                 cfg &= ~HPET_TN_ENABLE;
 324                 hpet_writel(cfg, HPET_T1_CFG);
 325                 return;
 326         }
 327
 328         if (PIE_on && (PIE_freq > DEFAULT_RTC_INT_FREQ))
 329                 hpet_rtc_int_freq = PIE_freq;
 330         else
 331                 hpet_rtc_int_freq = DEFAULT_RTC_INT_FREQ;
 332
 333         /* It is more accurate to use the comparator value than current count.*/
 334         ticks_per_int = hpet_tick * HZ / hpet_rtc_int_freq;
 335         hpet_t1_cmp += ticks_per_int;
 336         hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
 337
 338         /*
 339          * If the interrupt handler was delayed too long, the write above tries
 340          * to schedule the next interrupt in the past and the hardware would
 341          * not interrupt until the counter had wrapped around.
 342          * So we have to check that the comparator wasn't set to a past time.
 343          */
 344         cnt = hpet_readl(HPET_COUNTER);
 345         if (unlikely((int)(cnt - hpet_t1_cmp) > 0)) {
 346                 lost_ints = (cnt - hpet_t1_cmp) / ticks_per_int + 1;
 347                 /* Make sure that, even with the time needed to execute
 348                  * this code, the next scheduled interrupt has been moved
 349                  * back to the future: */
 350                 lost_ints++;
 351
 352                 hpet_t1_cmp += lost_ints * ticks_per_int;
 353                 hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
 354
 355                 if (PIE_on)
 356                         PIE_count += lost_ints;
 357
 358                 if (printk_ratelimit())
 359                         printk(KERN_WARNING "rtc: lost some interrupts at %ldHz.\n",
 360                                hpet_rtc_int_freq);
 361         }
 362 }
 363
 364 /*
 365  * The functions below are called from rtc driver.
 366  * Return 0 if HPET is not being used.
 367  * Otherwise do the necessary changes and return 1.
 368  */
 369 int hpet_mask_rtc_irq_bit(unsigned long bit_mask)
 370 {
 371         if (!is_hpet_enabled())
 372                 return 0;
 373
 374         if (bit_mask & RTC_UIE)
 375                 UIE_on = 0;
 376         if (bit_mask & RTC_PIE)
 377                 PIE_on = 0;
 378         if (bit_mask & RTC_AIE)
 379                 AIE_on = 0;
 380
 381         return 1;
 382 }
 383
 384 int hpet_set_rtc_irq_bit(unsigned long bit_mask)
 385 {
 386         int timer_init_reqd = 0;
 387
 388         if (!is_hpet_enabled())
 389                 return 0;
 390
 391         if (!(PIE_on | AIE_on | UIE_on))
 392                 timer_init_reqd = 1;
 393
 394         if (bit_mask & RTC_UIE) {
 395                 UIE_on = 1;
 396         }
 397         if (bit_mask & RTC_PIE) {
 398                 PIE_on = 1;
 399                 PIE_count = 0;
 400         }
 401         if (bit_mask & RTC_AIE) {
 402                 AIE_on = 1;
 403         }
 404
 405         if (timer_init_reqd)
 406                 hpet_rtc_timer_init();
 407
 408         return 1;
 409 }
 410
 411 int hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
 412 {
 413         if (!is_hpet_enabled())
 414                 return 0;
 415
 416         alarm_time.tm_hour = hrs;
 417         alarm_time.tm_min = min;
 418         alarm_time.tm_sec = sec;
 419
 420         return 1;
 421 }
 422
 423 int hpet_set_periodic_freq(unsigned long freq)
 424 {
 425         if (!is_hpet_enabled())
 426                 return 0;
 427
 428         PIE_freq = freq;
 429         PIE_count = 0;
 430
 431         return 1;
 432 }
 433
 434 int hpet_rtc_dropped_irq(void)
 435 {
 436         if (!is_hpet_enabled())
 437                 return 0;
 438
 439         return 1;
 440 }
 441
 442 irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 443 {
 444         struct rtc_time curr_time;
 445         unsigned long rtc_int_flag = 0;
 446         int call_rtc_interrupt = 0;
 447
 448         hpet_rtc_timer_reinit();
 449
 450         if (UIE_on | AIE_on) {
 451                 rtc_get_rtc_time(&curr_time);
 452         }
 453         if (UIE_on) {
 454                 if (curr_time.tm_sec != prev_update_sec) {
 455                         /* Set update int info, call real rtc int routine */
 456                         call_rtc_interrupt = 1;
 457                         rtc_int_flag = RTC_UF;
 458                         prev_update_sec = curr_time.tm_sec;
 459                 }
 460         }
 461         if (PIE_on) {
 462                 PIE_count++;
 463                 if (PIE_count >= hpet_rtc_int_freq/PIE_freq) {
 464                         /* Set periodic int info, call real rtc int routine */
 465                         call_rtc_interrupt = 1;
 466                         rtc_int_flag |= RTC_PF;
 467                         PIE_count = 0;
 468                 }
 469         }
 470         if (AIE_on) {
 471                 if ((curr_time.tm_sec == alarm_time.tm_sec) &&
 472                     (curr_time.tm_min == alarm_time.tm_min) &&
 473                     (curr_time.tm_hour == alarm_time.tm_hour)) {
 474                         /* Set alarm int info, call real rtc int routine */
 475                         call_rtc_interrupt = 1;
 476                         rtc_int_flag |= RTC_AF;
 477                 }
 478         }
 479         if (call_rtc_interrupt) {
 480                 rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
 481                 rtc_interrupt(rtc_int_flag, dev_id);
 482         }
 483         return IRQ_HANDLED;
 484 }
 485 #endif
 486
 487 static int __init nohpet_setup(char *s)
 488 {
 489         nohpet = 1;
 490         return 1;
 491 }
 492
 493 __setup("nohpet", nohpet_setup);